Refraction Methods to Research Transparent Nonuniformity
Refraction methods include the direct shadowgraph method; the Schlieren method, the raster method, and the interferometric method. All these methods use the variation of refractive index when the irregularity in medium occurs. The direct shadowgraph method records the second derivative of the refractive index; the Schlieren method records the first derivative; the interferometric methods record the change itself of medium refractive index.
- Flow visualization in Mach numbers range from 0.2 to 15.
- Direct shadowgraph method provides registration of nonuniformity at medium density to start with one kg/m3.
- Schlieren and interferometric methods provide registration of nonuniformity at medium density to start with 10−2 kg/m3.